Mainly, steel crawlers have conventionally been utilized as crawler mounted in transportable type construction machines, etc. Rubber shoes have been used in some of the steel crawlers. Recently, rubber crawlers are preferably utilized.
FIG. 1 is a sectional view showing an example of conventional steel crawlers; 11 is an outer flanged rolling wheel, 12 is a steel crawler shoe, 12a is a shoe plate, 12b is a shoe link, 12c is a linkage pin, and 12d is a lug (steel made).
FIG. 2 is a sectional view showing an example of rubber shoe; 13 is a rubber shoe, 13a is a shoe plate, 13b is a shoe link, 13c is a linkage pin, and 13d is a rubber lug.
FIG. 3 is a sectional view showing a conventional rubber crawler; 14 is a rubber crawler, 14c is a lug, 15 is a core member, and 16 is a steel cord.
In FIGS. 1 through 3, the same outer flanged rolling wheel can be concurrently used as rolling wheel in any case.
Hence, steel crawlers have the following advantages;
(1) its vibration is small because a continuous rolling track is obtained by combination of the track link at the inner circumference,
(2) Crawler come-off is scarce because there is no elongation nor phase error in the circumferential and width directions, and
(3) the durability is good because mechanical combination of respective links, etc. is large,
On the contrary, the steel crawlers inherently have the following disadvantages;
(1) Noise level is high, PA1 (2) Cushioning is not good, and an operator is subjected to a great deal of fatigue, and PA1 (3) Road surface is much damaged. PA1 (1) Noise level is low, PA1 (2) Cushioning property is good, and fatigue of an operator is low, PA1 (3) Road surface is not damaged, and PA1 (4) The weight is comparatively light, and the running speed can be made comparatively high according thereto and in line with the above properties. PA1 (1) Core members which project on the inner circumference at every fixed interval are provided and utilized as rolling track. Accordingly, rolling wheels are likely to drop between the fore and back projections, thereby causing the vibration to be made somewhat large, PA1 (2) Owing to that steel cords as elongation resisting member are buried slightly wave-like, and a thin rubber layer intervenes in the intermediate portion in the piled up area at both the ends of these steel cords, the crawler may be elongated when a remarkably high elongating force is given in the circumferential direction or the crawler itself may be distorted between the core members when an external force is given in the lateral width direction or come off due to those causes, and PA1 (3) The mechanical strength of rubber crawlers is based upon rubber substance, and adhering force between core members and steel cords, and it is influenced upon the adhering force at the boundary between metal and rubber. The mechanical strength is much inferior to that of the steel crawler. Accordingly, the durability of rubber crawler is inferior to that of steel crawler. PA1 (1) The adhering point between shoe plate and rubber lug will be the weakest point in the composition of steel crawlers, PA1 (2) As the rubber shoe will be composed that it is compressed between the shoe plate as steel structure and the ground and will have no space of escape, damage of the rubber lug will be promoted, PA1 (3) As the shoe plate is considerably spaced toward the outer circumference to a linkage pin at a part where the shoe plate is wound and turned over, the interval between the fore and back shoe plates will be opened. For that reason, it is impossible to continue the rubber lug across the interval of shoe plates, and soil and mud may enter between shoe plates on weak road surface to cause a shortage of floating. In order to improve this, if the width of shoe plate is increased to reduce the ground-contacting pressure, the total weight may be also increased, instead, its bouyancy is lowered and it will be a change for the worse. PA1 (4) Method for press-vulcanizing individual shoe plates by metal mold will bring remarkable cost-up. PA1 (1) As a track link will be combined and will become a continuous rolling track at the inner circumferential side of the crawler body, vibration will be made smaller during use of a vehicle in which the corresponding crawler is adopted. PA1 (2) Such a composition that a pin is fitted and inserted in a pin hole which lies fore and back of respective track links opposed to each other, and both the side ends of the pins are buried in the crawler body will make it strong the combination of the crawler body with the track link, and at this time, since the track links are mechanically combined strongly, the following advantages can be further obtained. PA1 (3) As the track link will be made a rolling track, use of core members indispensable for the conventional rubber crawler can be excluded. PA1 (4) As steel cords and core members are not needed, cost-down can be accomplished to a large extent as total. PA1 (5) Since a projection of core member is no more needed, a metal mold will be made thinner in thickness than the conventional ones. Therefore, further cost-down can be attempted at such a standpoint as the heat transmission can be increased. PA1 (6) As track links which have been used in part of conventional steel crawlers can be used as they are, it is very advantageous. PA1 (7) As the central portion of core member can be formed to any sectional shape regardless of the tooth bottom of a drive wheel, production cost of the core member is comparatively cheap.
However, rubber crawlers have such advantages as mentioned below;
But, the rubber crawlers have the following shortcomings;
From such circumstances, rubber shoe composed so that rubber lug is provided at the grounding side of shoe plate of the steel crawler has been partially utilized. The rubber shoe. As for the rubber shoe, it is made so that a shoe plate and non-vulcanized rubber are arranged in position in a metal mold and are press-vulcanized, and a rubber lug is adhered to the surface of the shoe plate at the same time as that of the vulcanizing molding.
However, in such a rubber shoe,
As a result, such an improved rubber crawler will not be what is superior to mere rubber crawlers.